If your facing an issue attempting to view segments, it may be the role/ group your API key has been assigned to does not have the rights under profile management to view segments and or manage segments.  

which /GET calls are you attempting to perform?

When it comes to events within the Adobe RTCDP platform the minimum payload is required. { "_id": "unique identifier","timestamp": "ISO time stamp of when event occured""identityfield": "string" }  The timestamp value of the event can be a current, prior, or future timestamp.  As noted in your use c...

The issue could be due to the technical account id has not been mapped into the role with the access controls. (AEP > permissions > roles).  I would look here and add your developer technical account id

here is the status of the lifecyle and how they are set. https://experienceleague.adobe.com/docs/experience-platform/segmentation/faq.html?lang=en#what-do-the-different-lifecycle-states-represent%3F

can you provide the format of the field which you are attempting to map the string value into? The date function will convert a date string into a ZonedDateTime object (ISO 8601 format). https://experienceleague.adobe.com/docs/experience-platform/data-prep/functions.html?lang=en#date-and-time

Can you copy and paste the error message to the thread?  The image appears to be unreadable.

Hello Have you created an offer which is json (text only based)?  Have you attempted to use the assurance module of Data Collections to see what is being rendered in the decision scope?

This error message is an indication the whitelist of IP addresses has not been granted for the storage location. Adobe recommends that you add the following IP ranges to an allowlist prior to working with cloud storage destination connections. Failing to add your region-specific IP range to your all...

if the requirement is to activate segments to a non-out of the box destination then using the Destination SDK to activate an audience is your best bet.  It also depends on the third party which you are attempting to activate to.  Most third party solutions will use a storage container to accept audi...