You can‘t force them to do an apprenticeship. The quotas of drop outs are much higher among asylum seekers than others, which is mainly due to two reasons: 1) they speak little to no german, so you need an additional ~3 years to get them to the level where they can communicate well enough to even have a chance and 2) the salary is bad, often less than what they get from the Jobcenter

Asylum seekers are automatically covered by GKVs after 15 months, so the numbers from 2019 include the majority of asylum seekers since most came in 2015. There are also agreements in place between GKVs and many Bundesländer that asylum seekers are covered right away.