I couldn't find any information about the size of Filemaker Go. The specs I founds states that Go requires iOS 5.1.1 or later. You should be able to verify this from iTunes or under settings on your phone.
I don't have a iPod but I understand when you connect to iTunes it states how much space your have available and on my iPhone I can go Settings, General and then about my phone displays the amount of space available. When I backup my iPhone to iCloud it shows Go being 19.2MB. I deleted some of the sample databases that come with Go, so I would guess 45mb would be enough space on your iPod. I'm just guessing about that.
If your iPod is full you may have to backup your photos/music to the cloud or to your computer with iTunes and then delete some of the photos or music from the iPod.
Thank you for your post.
From the home page of your iPod touch, tap Settings. In the Settings menu, tap "General". In the General menu, tap "About". This next screen will give a lot of information about your iPod touch. Look under Capacity to see how much your iPod touch will hold. Just below that will let you know how much room is still Available. FileMaker Go takes up 805 MB, so make sure you have 1GB available as a minimum as this would accommodate the FileMaker Go application plus another 200 MB for any local FileMaker Pro files you place on the iPod touch.
I couldn't find any information at all, and my guess was way off.