Cannot add a Nextcloud account in Unity desktop

I am using Ubuntu 20.04 LTS with Unity desktop and I have the following issue:

There is an option to connect a Nextcloud account as an Online Account.

https://i.stack.imgur.com/dDHbI.png

I enter the needed server name, username and password; but there’s no button to press.

https://i.stack.imgur.com/gTBoW.png

Is there a workaround?

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: unity 7.5.0+20.04.20200312-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
Uname: Linux 5.4.0-48-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.capabilities.gpu0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/capabilities/gpu0'
.proc.driver.nvidia.capabilities.mig: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/capabilities/mig'
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 450.66 Wed Aug 12 19:42:48 UTC 2020
 GCC version: gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)
.tmp.unity_support_test.0:

ApportVersion: 2.20.11-0ubuntu27.9
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity:Unity7:ubuntu
Date: Sun Oct 4 12:11:36 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
DkmsStatus:
 nvidia, 450.66, 5.4.0-47-generic, x86_64: installed
 nvidia, 450.66, 5.4.0-48-generic, x86_64: installed
 virtualbox, 6.1.10, 5.4.0-47-generic, x86_64: installed
 virtualbox, 6.1.10, 5.4.0-48-generic, x86_64: installed
GraphicsCard:
 NVIDIA Corporation GP107 [GeForce GTX 1050 Ti] [10de:1c82] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Micro-Star International Co., Ltd. [MSI] GP107 [GeForce GTX 1050 Ti] [1462:3351]
GsettingsChanges:
 b'org.compiz.core' b'active-plugins' b"['core', 'composite', 'opengl', 'place', 'regex', 'resize', 'session', 'snap', 'vpswitch', 'wall', 'animation', 'commands', 'compiztoolbox', 'copytex', 'fade', 'grid', 'imgpng', 'mousepoll', 'move', 'scale', 'unitymtgrabhandles', 'workarounds', 'expo', 'ezoom', 'unityshell']"
 b'com.canonical.Unity' b'minimize-count' b'100'
 b'com.ubuntu.user-interface' b'scale-factor' b"{'HDMI-0': 8}"
 b'org.gnome.desktop.interface' b'gtk-im-module' b"'gtk-im-context-simple'"
InstallationDate: Installed on 2020-08-20 (44 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
MachineType: System manufacturer System Product Name
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-48-generic root=/dev/mapper/vgubuntu-root ro quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/30/2008
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0638
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: P5B-E Plus
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0638:bd09/30/2008:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP5B-EPlus:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: To Be Filled By O.E.M.
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
version.compiz: compiz 1:0.9.14.1+20.04.20200211-0ubuntu1
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.8-0ubuntu1~20.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 20.0.8-0ubuntu1~20.04.1
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2.4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1