Mh, I just checked my GoG page, and it should indeed by the standard CD-ROM version. Onle WC4 is the DVD version, I think.
Launch problems in any game might be related to storage access restrictions implemented by Google with the Android 12/13 updates, so it might be worth running the initial DOSBox setup again.
Before you do so, and start moving/copying game files all over your phone, you might want to check your mountings, though. I have my game stored on an external sd card, and it’s running fine.
The game itself as well as the DATA.DAT (the CD-ROM image file from GoG) is in a subfolder called “/Games/PC” on my external sd, which is labelled “0000-0000”. For reference, these are the contents of my expert settings section:
mount c: /storage/0000-0000/Games/PC
imgmount d /storage/0000-0000/Games/PC/WC3/DATA.DAT -t iso