Are you able to place custom code on the site? If you are able to add
the header and footer code, DTM should work. If you are unable to add
just the footer code, you might still be able to deploy it since the
page bottom function is called on DOM Ready if it's isn't found on the
page. With that said, DTM is considered a legacy product at this point
and all new implementations are encouraged to use Launch. You can learn
more on the Launch, by Adobe community.