If you plan to make this for VTT. The beginning of the tutorial gets you to set up your map space for an 18" x 24" map, for tactical scale of 1" = 5'.

Once you complete your map choose File/Save As

For PNG, when menu opens, first select from drop down "True Color + Alpha", if you have an requirements for transparency, though the dungeon as per tutorial doesn't require transparency.

Then go to the next tab, Bitmap size - this is where you set the actual pixels per inch scale for VTT, choose whatever you think you need 20, 50, 100, 200, though the last two make for very large files. Ideally you don't want your final file to be over 1 MB for VTT. But I get VTT users that ask for 200 ppi all the time.

Go to the options tab and insure the "Transparency" is checked on, again if you have any needs for transparency in your PNG file.

Then select "Export" at bottom of menu.

For JPG, the color menu can only be true color (no transparency option available). In the Bitmap size - same as above to scale to your VTT app needs and allowances.

Options tab, JPG can be reduced in color gamut to minimize file size, but the more compressed the crappier the result. So try not to go below 50%, instead try around 70%. Doing so can significantly reduce the file size.

Export.

That's it!

GP