Can't install D2 - LOD because installer says I don't have the base game? I do have it

I just bought Diablo II and LOD from the Blizzard Store. Installed D2 and it’s working fine. However, I just tried to install LOD and the installer says I must install D2 first. I tried putting the LOD install files/folders directly into my D2 directory, but it still thinks I don’t have D2.

Any help would be appreciated. Windows 10. Thanks.