Yes, Cura 4.6 opens the file and gives the "Your Model is not manifold" error, but the print seems to come out fine.
Probably because the error is in some place not visible or because it is a very small problem.
In the course of researching this issue, I came across a free online service (Jomatik) that corrects these Holes and other issues with 3D files making them ready for 3D Printing.
Check the following link.
Just drag and drop your file there and it instantly repairs it. Well.... atleast it did mine. 🙂
The file now loads up in Cura without any errors