Third party submissions for ATF eForm 1's are not authorized for ATF eForm 1 applications. In the included photo the ATF gives the denial reason for using services that advertise to automate ATF Form 1 service.
When the ATF processes your credit card and the credit card is declined for suspicious activity, not enough funds, etc, your application will be denied. This means that you will need to start the application process all over again and submit a new application to the ATF for your ATF Form 1 or ATF Form 4 tax stamp.
You can't use a digital signature or signature font to sign the name of the responsible person. If you attach your ATF 5320.23 using a digital signature, the ATF will send you a correction email and you will need to go back into your application and reupload the ATF 5320.23 that has an original signature.
When you receive an approved ATF eForm 1 application, you will receive an approved tax stamp with "FORM 1 REGISTRATION, UNITED STATES" in box 4a. This may seem counterintuitive or as an error, since if you were to apply using the paper ATF Form 1, the applicant information/applicant entity information will be there. This however, is correct and how the ATF eForm 1 application handles Form 1 registrations, where the applicant/applicant entity is the maker.