Where can I get the VTK 8.90?

VTK 8.90 is not an official release of VTK, which means that even if you use a VTK which declare this version in the CMake, there is no guarantee that everything will work (both in the VTK and OpenCV side).
Anyway, here is a git tag I used for some projects during the 8.90 time : e4e8a4df9cc67fd2bb3dbb3b1c50a25177cbfe68

Looking at this CMake, it seems that OpenCV may also work with VTK 8.2. This is on older release, but if my guess is right that would be more stable.