Anglers besides being bizzare are deep water fish and get along with most any fish with exception of those it can swallow, On the eel, as long as eel is not large like a wolf or moray capable off swallowing it, I dont see an issue. The most common cause of death in Frogfish in captivity is overfeeding as a hungry frog will start fishing and walking about the tank hunting which is a signal to feed it again. Sometimes you have to let them beg than let it get overfull.
Those 2 would be fine together, neither would pose a threat to the other, but their needs may be best in different tanks. A ribbon eel needs a 6' tank and if your tank is that larger, other tank mates would need to be carefully chosen if a warty is included. Both will eat small fish, the warty as large as themselves and the ribbon eel will take down small slender fish like wrasses and such, not larger fish though. Anything you would put in say a 125g could not be aggressive enough to pick on the warty, or too aggressive to pick on the ribbon either. Feeding the warty in a tank that large would also be a challenge, regardless of the "train your frogfish" school of thought, these guys will live a much longer and happier life eating live food; as well as being more entertaining. So getting food to them in a larger tank especially with rambunctious tank mates sometimes proves difficult(not impossible just difficult), warty's are much more fun in a 20-30g species tank. Don't think to put the ribbon eel in a tank smaller than 6', this eel gets to about 4' and can really enjoy swimming around, they also do best with live food included in their diet. So what size tank are talking about?
WELCOME!!! I think you will be fine with that pair as well. But, knowing frogfish, I'd be more worried about your ribbon ell getting snacked on by the frogfish...