Updates cannot be installed

Im running BTT on a relatively older MacBook Pro under OSX High Sierra. Since a time updates cannot be installed, so I have to download the newest version from the website manually. Unfortunately, the V3.55 insn´t available there...
Same is with updating the DefaultFolderX-software, so I think there is a problem with the Updater used by both of these apps.
Someone had this problem before? Any solution?
Thanks for any suggestions!

I think the auto updater is fine, but possibly I haven’t put it on auto update for high sierra yet. I’ll check that. (I don't use that macOS version anymore, thus the builds are not tested well on it).

You can access any BTT version via https://folivora.ai/releases

Thanks a lot for the link!
Unfortunately I cannot update my MacBook Pro to a higher macOS-version because it's from 2010. I Tried the patched OSs from dosdude but they crash too often.