Looks like a mistake in your syntax

https://server/laserfiche/Browse.aspx?repo=Repository#?id=3;view=newroot

https://server/laserfiche/Browse.aspx?repo=Repository#?id=3&view=newroot

FYI, The lastest URL info is located  the Documentation here
https://doc.laserfiche.com/laserfiche.documentation/11/userguide/en-us/Default.htm#../Subsystems/client_wa/Content/ShortcutsURLs/URLs.htm?Highlight=custom%20URLs

Specific to you

Open to a Specific Folder
You can create a link that will open the Laserfiche web client directly to a specific folder. To do so, use the following URL:

https://ServerName/laserfiche/browse.aspx?db=dbName#?id=EntryID
where dbName is the name of your repository and EntryID is the entry ID of the folder. You can find the entry ID in the Laserfiche web client in the Metadata tab of the details pane, under Show advanced. This URL can also be obtained by navigating to the folder and opening it in the Laserfiche web client, then copying the URL from the address bar.

You can also choose to show the specified folder as the root of the repository. Folders other than the specified folders and its children will not be displayed in the folder tree. To do so, use the following URL:

https://ServerName/laserfiche/browse.aspx?db=dbName#?id=EntryID&view=newroot
Note that the new root URL option will only take effect if the link is used when the user is logged out; it will not take effect if used while a user is logged in.