If you really want to make a per-user installer that does not require admin permissions, the correct settings to use are:
[Setup]
PrivilegesRequired=lowest
DefaultDirName={userpf}\YourAppName
Note that (addressing Glytzhkof's concerns) this is a local folder, not a roaming folder. If you want settings to roam then you will still need your application to keep them in (your language's equivalent of) the {userappdata}\YourAppName
folder. Regardless, the user will have to separately install the software on each machine that they intend to use it on (but this is typically the best option anyway).
Some of the downsides of making a per-user application are:
You cannot use admin permissions when installing. In particular this means that you cannot install many other components (runtimes, libraries, etc) that you might have wanted to use in your application. You also can't use features like
regserver
andrestartreplace
. (This doesn't necessarily mean that you cannot still use these components, just that it's a larger hassle if the user does not already have them installed.)If a single machine has multiple users (common for families and in some workplaces) then they will have duplicate independent copies of your application, which have to be individually upgraded by each user. This particularly annoys IT departments as they prefer doing central upgrades, and if your app is large it may waste disk space.
If the reason you don't want to make a normal {pf}
based application is simply that you want to be lazy and store settings files in the program's folder, then it's probably better overall to rethink this decision. It's not hard to do it "right".