Hi welcome to the forums.
/Topology/ is the word used in networking to describe how things are connected to each other.
In WiFi, the term /Mesh/ is used to describe the topology where LAN /accesspoints/ are talking to each other wirelessly (e.g. 802.11s), in addition to clients (user /stations/ in wifi terminology) and relaying the user data over the air, perhaps multiple times if necessary.
In your case, you have a wired /backhaul/ from Ethernet jacks in each room into the basement, you don’t have to care about meshing.
What you want is a LAN with multiple access-points that’d allow your phone/laptop other devices to roam (disconnect from old / connect to new) access point with minimum disturbance to you.
To achieve that, it’s best to configure all 5 accesspoints (in your case the 4x MR2200 and one router) with the same /SSID/ and password. This is the de-facto standard way of telling client devices that these are just multiple access-points connected to the same LAN and that they don’t need to reset any TCP sessions or ask for new IPs.
Ideally, your accesspoints would run on non overlapping wifi channels to minimize interference from each other and maximize the amount of air time available for each clients data.
Your accesspoints don’t have to be aware of each other at all, as long as you configure them correctly once.
They don’t have to be the same model or be made by same manufacturer even.
That’s it.
802.11r
There’s an extension to various wifi standards called 802.11r that can make this “roaming”/“handoff”/“fast-transition” process easier for clients that support it (most still don’t) which complicates things dramatically, but might save a few milliseconds.
In this case, your APs need to notify the client about MAC addresses of neighboring APs and your client can look for them and once it finds them can maybe switch more quickly (terms used are FT over air; or FT over BS; the difference is whether you authenticate to new access point with better signal by talking to it over the air; or by talking to current access point that you’re already connected to perhaps poorly)
Even if your client device claims to support 802.11r, your user experience might suck when it’s transitioning from one accesspoint to another e.g. latency spike in the middle of a video call or a phone gaming session.
Mostly because your phone needs to tune out its single radio to look around for a better access point on other frequencies.
Synology MR2200 does support it, you can try it.