1. Enter svn in the terminal to see if svn is installed
2. If svn is not installed like me, execute sudo apt install subversion
3. When using svn check out for the first time, it will directly prompt to enter the account password.
4. If you want to modify the account and password of svn, delete all files in the directory ~/.subversion/auth/. The next time you operate svn, you will be prompted to re-enter your username and password. Just replace it with what you want. Then the system will record it by default.