Hi, Karen. Visit the Cain/Caine surname project at https://www.familytreedna.com/groups/cain-caine/about. There, on the left-side submenu--not the tab labeled "Results," but on the menu--you'll see an option for "DNA Results." Choose "Classic Chart" or "Colorized Chart." You can search for your brother's kit number; it's about a third of the way down the page. You'll see him grouped with several other Cains, and the STR values for those test kits are displayed.
I like to keep track of those surname project matches in an Excel spreadsheet so I can more easily compare the actual results side by side. Because STR markers don't mutate at the same average rate, I occasionally search for new estimated mutation rate information and add that to the spreadsheet for reference. If you'd like a copy of the template, send me a private message from my profile page so that I'll have your email address.
I'm firmly with Peter that yDNA SNP testing is not needed on your brother for your stated purpose. FTDNA's predicted haplogroup is pretty accurate as far as it goes, and there need to be specific reasons to dig deeper into subclade information. Just being curious and interested is a valid reason, though. :-)
Used to be the yDNA haplogroup differentiations were shallow enough that just a few letters and numerals, like "R1b1a1a2"...which is equivalent to you brother's predicted haplogroup of R-M269, would suffice. The trend now--and FTDNA is using it--is to use that "terminal SNP," in other words the deepest one tested and confirmed positive, as the haplogroup. For example, I'm R-BY3332, which is several steps deeper down the phylogenetic tree from, but on the same branch as, R-M269.
When you see matches that list something other than R-M269, there are two resources to help you determine if the match is deeper in the same subclade (which is a green light for you), or significantly different at a higher level. If significantly different, the two individuals are extremely unlikely to be related in the genealogical timeframe. For example, and R-M269 (R1b1a1a2) will be related to an Z283 (R1a1a1b1) only in an anthropological timeframe.
Sounds more confusing than it is. Sorry 'bout that. One place to compare is at the ISOGG's yDNA Haplogroup Tree: https://isogg.org/tree/. Click on the top-level haplogroup letter, in your case "R", and search for the SNP you're interested in (oh, and leave off the "R-" when you search; it isn't used).
The ISOGG tree is still considered a de facto standard, but it isn't modified as quickly as new markers are added to the taxonomy. For example, my BY3332 terminal SNP doesn't appear yet on the 2017 tree. A more complex reference is Alex Williamson's "Big Tree" at http://www.ytree.net/. If you see a haplogroup associated with a match to your brother's kit and can't find it anywhere else, you can look here. One simple trick is to use Google Advanced Search and construct the search term exactly like this (using my SNP as an example):
That searches for the exact SNP string, and limits the search to the Big Tree's website. Very useful.
Edited to add: again I spent too much time typing and Peter beat me to it. :-)