As mentioned in the Filters section, data accessed from URL params (query strings) and form inputs, can be accessed with Users Anywhere by using the input:... Data Tags.
For example, when passing a usergroup via URL with a custom input parameter, like:
https://www.mysite.com/my-users?myparam=Herd
You can then filter by that parameter, and display it in the output:
{users usergroup="input:myparam"}{if is-first}This is a list of users in the user group: [input:myparam]{/if}
• [title]
{/users}
You can also use this in If Structures, to conditionally output content based on the input value. For example, to show a "LOCAL!" label for all users that have "Belgium" set as their country, you could add a custom ?local=Belgium parameter, and then do:
{users usergroup="Customer"}
[title] {if country=input:local}LOCAL!{/if}
{/users}
Or, for example, you can use this to only provide access to user images via a URL key (such as ?pass=ABC123):
{users usergroup="Customer"}[title]
{if input:pass="ABC123"}
[contact:image]
{else}
This images is password restricted!
{/if}
{/users}
Note: If you're using Joomla cache (via Global Configuration, not via the System Plugin), you will need to register these additional URL Parameters as "safe", in order to make Joomla create a unique cache for each page. Users Anywhere allows you to do this in the "Advanced" tab of the plugin settings (for each extra parameter name, you should also specify what type of value it can be).