Adobe Acrobat Reader...Safe to download to MBP??

If you download it from the Adobe site, yes.

Reader is safe but the newest versions get you thoroughly involved with the Cloud. If you want to keep it local, you need an earlier version and Adobe makes them very hard to find. Reader 10 is the earliest that's still available and does work in El Capitan (I just tried it.) The installer is at Adobe's ftp site: ftp://ftp.adobe.com/pub/adobe/reader/mac/10.x/10.1.2/en_US/
and I believe it's the highest which will update directly to its latest version of 10.1.16. Once installed, just tell it to check for updates.

The comment about the free, Adobe Acrobat Reader getting you involved with the cloud only applies if you specifically choose to sign up for optional Adobe PDF services, or purchase Acrobat DC Pro via its subscription service, or a one-time purchase.

Otherwise, Acrobat Reader DC is a local entity. Since Adobe applies security fixes to Acrobat products, just as it does to Flash releases, it is wise to stay current with the latest Reader updates. I do, and do not have Adobe cloud stuff in my face at all.