You can't get Get-ScheduledTask at windows 2008 R2 as it was introduced for Windows 2012 and nobody backported it. For more see the link at github.
The comment that describes the situation the best is:
Hi @dronkoff - This module is supported on PS 4.0. However, the problem isn't in the version of PowerShell. The issue is that the ScheduledTasks module, which this resource depends on, is not built into Windows Server 2008R2. It was first included in Windows Server 2012.
This is the case with many of the PowerShell modules: They are missing from older versions of Windows (Networking for example). In the odd occasion there is an easy work around. However in this case converting the resource over to use schtasks.exe is not possible without a complete rewrite and would probably result in something really unstable and buggy (not to mention the problems that would arise with different localized versions of schtasks). I really can't see this happening unfortunately (unless someone else from the community has some ideas on how to do this).
But you are correct, this should be mentioned that Windows Server 2008R2 is not currently supported.
The workaround
The way around it, is to use schtask with correct switches.
If you have it in the Microsoft folder as I have it in the example you just need to run:
schtasks /tn \Microsoft\ServiceNow /query /fo LIST
The output:
Folder: \Microsoft
HostName: XXXXXACL06
TaskName: \Microsoft\ServiceNow
Next Run Time: 7/4/2018 8:16:22 AM
Status: Ready
Logon Mode: Interactive only
If you want more details you can use the /v (verbose) switch:
schtasks /tn \Microsoft\ServiceNow /query /v > service_now_details.txt
Edit - to find a pattern
If you have only pattern to search you have to use some additional tool to search the string. The windows natively supports findstr (or Select-String (short sls) in powershell):
To find the task name you can use then:
schtasks /query /fo LIST | findstr "ServiceNow"
OR even with wild charter
schtasks /query /fo LIST | findstr "ServiceNo*"
OR the powershell way:
schtasks /query /fo LIST | sls 'ServiceNo*'
The output in all cases will be something like this (since my task is named exactly ServiceNow):
TaskName: \Microsoft\ServiceNow
Edit2 case sensitivity
If you are searching for case insensitive string then:
for findstr you have to add /I to make it insensitive. The powershell's select-string (sls) is naturally insensitive.