unable to open the link for a construction app called building connected
Building connected application will not open
iMac 21.5″, macOS 10.15
You can try clearing the cookies and website data:
Manage cookies and website data in Safari on Mac - Apple Support
That website claims they support Safari 14 and later so that should not be a compatibility problem with Catalina having Safari 15. It may be necessary to contact them for problems with their website.