The IDE is being discontinued. So there’s no reason to use it anymore and many of the features no longer work.
In particular, you can no longer add new DTHs. Those are ALL being discontinued.
Instead, the smartthings platform now uses “edge drivers“ which will run on your own hub.
Start by reading the following community FAQ. It includes links to all of the official announcements about this.
FAQ: I have no idea what Edge is. Is that a new developer tool? (2022)
Then read the following thread, to find out how to do specific things you used to do with the IDE:
Life after the IDE: Questions and Answers
but read the edge FAQ first, or the second thread won’t make any sense.