Looked around, but everyone seems to be getting a lot more information during their Readiness Check fails. Or have to do with installing/upgrading Magento, not installing components.
For me...I get nothing. This is what I get when trying to install any component (even the Sample Data ones):
Check Updater Application Availability: PASS
Check Cron Scripts: FAIL - No information provided; Cron Job has not been configured yet
Check Component Dependency: FAIL - No information provided; "We found conflicting component dependencies."
PHP Version Check: FAIL - No information provided; In everyone else's post it at least tells the freaking versions found
PHP Settings Check *: FAIL - No information provided
PHP Extensions Check: FAIL - No information provided; In everyone else's post it at least tells which extensions were not found
I've gotten the Cron stuff to run to the point where the Index Management reports all green. -- Lemme tell ya, I miss Magento 1.9. Where you could run the reindex from with in Magento's Admin.
I was getting this before and the Index was in need of reindexing, read that this likely why the Component Manager can't pass the Readiness Check. But it appears there's more that's still not right.
Magento 2 (version 2.1.1; FRESH INSTALL) installed via Softaculous