Can you please try again with the following query:
Select Top 1000000 tblAssets.AssetID,
tblAssets.AssetName,
tblADusers.Displayname,
tblADusers.Department,
tblAssets.Username As Login,
Case When tblAssets.AssetID Not In (Select tblSoftware.AssetID
From tblSoftware Inner Join tblSoftwareUni On tblSoftwareUni.SoftID =
tblSoftware.softID
Where tblSoftwareUni.softwareName Like '%Sketchup%') Then 'not installed'
Else 'installed' End As sketchup,
Case When tblAssets.AssetID Not In (Select tblSoftware.AssetID
From tblSoftware Inner Join tblSoftwareUni On tblSoftwareUni.SoftID =
tblSoftware.softID
Where tblSoftwareUni.softwareName Like '%autocad%') Then 'not installed'
Else 'installed' End As autocad
From tblAssets
Inner Join tblAssetUserRelations On tblAssets.AssetID =
tblAssetUserRelations.AssetID
Inner Join tblADusers On tblADusers.Username = tblAssetUserRelations.Username
And tblADusers.Userdomain = tblAssetUserRelations.Userdomain
Where ((tblAssets.AssetID Not In (Select tblSoftware.AssetID
From tblSoftware Inner Join tblSoftwareUni On tblSoftwareUni.SoftID =
tblSoftware.softID
Where tblSoftwareUni.softwareName Like '%Sketchup%')) Or
(tblAssets.AssetID Not In (Select tblSoftware.AssetID
From tblSoftware Inner Join tblSoftwareUni On tblSoftwareUni.SoftID =
tblSoftware.softID
Where tblSoftwareUni.softwareName Like '%AutoCAD%'))) And
tblADusers.Department = 'name'