The file fmp_trial_fm_126.96.36.199.dmg downloaded from http://fmdl.filemaker.com/TBUB/15/fmp_trial_fm_188.8.131.52.dmg is broken.
It is code signed (as it should), but the file was modified after signing, so the signature is invalid.
Also hdiutil can't verify the file content as the checksum for GPT header does not match.
Please replace the file as soon as possible to avoid new customers running into that issue.
macOS Sierra will not mount the disk image and recommend the user to delete it.