Under the Anti-Lobbying Act:
No part of the money appropriated by any enactment of Congress shall, in the absence of express authorization by Congress, be used directly or indirectly to pay for any personal service, advertisement, telegram, telephone, letter, printed or written matter, or other device, intended or designed to influence in any manner a Member of Congress, a jurisdiction, or an official of any government, to favor, adopt, or oppose, by vote or otherwise, any legislation, law, ratification, policy, or appropriation, whether before or after the introduction of any bill, measure, or resolution proposing such legislation, law, ratification, policy, or appropriation;
In other words, federal agencies cannot use appropriated money to lobby any official of any government. That said, there is a major exception to this:
but this shall not prevent officers or employees of the United States or of its departments or agencies from communicating to any such Member or official, at his request, or to Congress or such official, through the proper official channels, requests for any legislation, law, ratification, policy, or appropriations which they deem necessary for the efficient conduct of the public business,
Federal agencies are routinely expected to communicate with Congress about legislation affecting them. The agencies know much more than Congress about what they're doing, how well it's working, whether any legislation might help them do their jobs better, etc. Congress is of course free to disagree, and can get information from lobbyists as well, but it wants to have the agency's input. In fact, federal agencies generally have sections devoted to handling relations with Congress on a full-time basis. Agencies do tend to keep a pretty tight grip on who gets to talk to Congress, so subunits may or may not be allowed to handle legislative affairs, but it looks like SAMHSA does have a legislative director.
If the Act doesn't prevent official communications, what does it prevent? The DOJ's Office of Legal Counsel (whose opinions are in many ways treated like court rulings, especially over something like appropriations where courts are unlikely to ever get involved) has interpreted it fairly narrowly, to ban things like a mass letter campaign asking recipients to call their Member of Congress about proposed legislation. It has interpreted it to not prevent public speeches or writings, "even to the extent of calling on the public to encourage Members of Congress to support Administration positions."
There's also an exception for foreign policy and national security functions, but those don't really apply to SAMHSA.
Source: "Lobbying Congress with Appropriated Funds: Restrictions on Federal Agencies and Officials," Congressional Research Service report R44154.