I have been struggling with the administator side interface of Joomla4. But I found out, that I had not uninstalled the Joomla3 version, that was not active.
I uninstalled the extension, but while the database was gone, the information page remained.
I tried to take my chances and uploaded the ZIP. I generated an error, indicating that the folders were existing and not empty (bot front and Admin side)
So I renamed both folders using FTP, and retried.
YThat was simple, these errors did not appear again, but a new one appeared:
JLIB_INSTALLER_ERROR_COMP_INSTALL_DIR_API
I think that you may have a simple solution to enable installing Joomdb for Joomla 4.
Please help :-(
Leo