Hello Max,
Standard edition doesn't support equirectangular panoramas on input, however, you can use the source images per camera position and Camera Station concept instead:
if the images are acquired using the common camera mounted on the tripod with the calibrated nodal head, then group each sub-set of images to the separate camera folder in the Workspace pane, assign Camera Station class to each group and then start the camera alignment procedure. For fisheye cameras you should also set the corresponding camera type in the Camera Calibration dialog.
Camera station assignment can be applied to multiple camera folders in the Workspace pane.
If you use Add Folder option and the images corresponding to the camera stations are already grouped into some subfolders in some "master" directory, then upload loading images to the chunk they will be automatically put to the separate camera folders according to the existing file folder layout.