I have no idea why this happens…constantly! Why on earth do I need to sign in every time I use SketchUp? I do not have to sign in using AutoCAD. Today, after a three week break, I cannot sign in…doesn’t recognize my email or my password. I reset my password and nothing.
Please put meaningful information in your profile. This helps the people answering to give correct and accurate answers.
You need to sign in every 28 days to use certain features. I think you are using a Classic license with SketchUp 2021, and your email address is not a Trimble ID. When you do have to sign in to use features, such as Add Location, 3D Warehouse, or Extension Warehouse, you can use the sign in with Google, Apple, or Microsoft options. Don’t use the sign in with Trimble option.
If you use Google a lot your browser may well have stored your email address and password for you.