There are several different causes for the “address library not loading” error. This page covers those, and how to solve it.
Wrong address library version
You need to install All in one (Anniversary Edition), not All in one (Special Edition).
You used the downgrade patcher, and are running Skyrim Special Edition 1.5. If you did, go to steam, and verify Skyrim’s game files to install the latest version of Special Edition, 1.6.
Wrong game selection
When you launched Skyrim Together for the first time, you did not select SkyrimSE.exe when the selection popped up. You can fix this by going to SkyrimTogether.exe and double clicking it while holding spacebar. This should reopen the selection menu. Select SkyrimSE.exe this time.
If you still get this error, check the path located at the bottom of the error, and verify that address library is actually installed there.
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