ALMA data can be found in the archive. There, one can check if a source has been observed and with which settings, the data release date, as well as other key information.
In addition to this archive, there is the JVO ALMA archive, which allows to quickly check thumbnails of the final products as well as a sky view of the source position.
More detailed information on the ALMA Data webpage. Please, check at the end on the page the acknowledgement statement one must include, should you use any of these data.