As there is no product called ds808 it is clear that there is no adapter for it.

Are you sure you have an Autel device, not any bad fake copy ?

 Here you go.

https://www.controller.com/listings/aircraft/for-sale/1298721/1970-mcdonnell-douglas-dc-8-62

Sorry, I have just seen that there is as DS808 on the product page of Autel.

It is a smaller and striped down version of the MS906 and offers ONLY the OBD-II connector.

As the OBD-II is there for 16 years now I can see that most new customers do not need the old adapters and therefore Autel offers a product without them.

So if you need older cars you have to look a the MS9xx products.
MS906 with adapters,
MS906BT for coding and Bluetooth or MS906TS with TPMS support (Tigger, Read sensor ID:..)

Otherwise there are adapters on ebay or Aliexpress for OBD to BMW/Fiat and co. that might fit the DS808.

  Weird who would have figured shortly after the DS708 was discontinued, they announced the regular cabled MS906 was the replacement for the DS708 , and now they are selling what appears to slightly smaller screened platform than a MS906 , with a smaller battery, and  without an adapter kit called a DS808. The DS808 is priced about $300 less than than the MS906 that comes with the adapters. If the DS808 software hasn't had any coding and functionality reduced from mid 2014 spec  and if the DS708 adapters and cable can be put to use on a DS808, it would make sense to buy a DS808 to get newer car coverage and keep the older DS708 just in case some functionality of the older car coverage got compromised on the DS808.

 DS808 is the advanced version of DS708, it is only configured with OBDII connector, but has the same functionality with MS906. You can purchase the connectors of MS906 to use in DS808. 

 If I bought the DS808 and had to purchase the MS906 connector set for older OBD2 cars that still used OBD1 style connectors, I might as well just  keep my DS708 for that older stuff or just get the slightly larger MS906 and have the connectors or for the same money get a slightly older MS905 with blue tooth VCI ( that I believe is discounted  no longer being produced and the MS906 BT replaces it ) that Autel claims to have more advanced coding capabilities than either the DS708, 808, or cabled MS906, but I have seen no videos that show superiority of coding capabilities of the MS905 over a basic MS906 on the same vehicle with current software versions to support that claim.