This will likely require the 5.13 kernel. You can grab the 21.1 ISO:
If you don’t know what to do, you basically download the two part zip file, then extract it in the same directory!
For example, this is for KDE:
https://github.com/manjaro/release-review/releases/download/202107281031/manjaro-kde-21.1-210728-linux513.iso.z01
https://github.com/manjaro/release-review/releases/download/202107281031/manjaro-kde-21.1-210728-linux513.iso.zip
You download these two files in a folder, extract them both!