Being explicit, as @Jici recommends, is probably the best approach, as it allows you to choose the delimiter.
However, it’s worth knowing that Bubble will automatically convert a list into a comma-delimited string when that list is used in a string context (IF the data type comprising the list can be represented as a string).
So for instance, setting a text element to a list of images will result in a comma-delimited series of URLs. In your case, simply using the list of addresses in a string context will achieve your desired result.
SIDE NOTE: If any of the addresses contain commas - e.g. 123 45th Street, Unit B - that could result in unwanted side effects down the line, so beware. You might want or need to use something other than a comma as the delimiter.