First congrats on the new MAC!!
Now I presume you downloaded and installed Lightroom CLassic on the new Mac?
If so, look in the PICTURES folder and find your catalog (your catalog's name.lrcat) .
And it is easier to transfer (copy) your LR catalog and the associated .lrdata files to the mac first.
Second, where were the photo files themselves located when you were using the PC? Were these on the same drive or an external drive?
If they were on an external drive, you probably only need to connect the external drive, launch your catalog from the PICTURES folder, and probably follow the steps here to relink.
https://www.computer-darkroom.com/lr2_find_folder/find-folder.htm
If the photo files themselves were on the PC and they did not move, you. may need to physically move them!
On a side note if you double click the Photos Library.photoslibrary icon in the PICTURES folder, it just launches the PHOTOS application from Apple.
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