I think it would really help everyone if people here gave their location by country as the law may vary dependent on where you are.
In the UK you would be protected by the Disability Discrimination Act and the employer will need to make reasonable adjustments for you, but that would only really cover you if you told them of your disability so yes, you should disclose it to them.
It may be a bit early days for this but you should also inform your local area for the autism strategy group or whatever it is called to act as an advocate for you. They should be able to communicate with the employer as you are working there to see how things are going, and communicate back to you too. If there are issues to be addressed, from either side, it would go through this advocate.
The adjustments can often be very minor ones but will make a big difference. Unfortunately I have found employers often make their own "adjustments" without asking you first, which actually involves leaving you rather isolated, not telling you if there's a problem because they're scared of how you will react, and bottling everything up until they just hit you with hundreds of (mostly unjustified) complaints when you never knew anything was wrong, and either let you go or leave you so scarred that you can't work for them effectively.