Use #6 exterior screws, because #8 will be too large for the holes in the angle.
Advise using two on each end attach with screws.
Holes are about 0.168" and a #10 screw is 0.190" at shank and 0.130" at root of threads.
Can do that, but really needs stronger fasteners than this can provide.
assuming you are using 2x8 as joist and trying to rest the 2x8 on top of the 4x4 post, you need post cap. Similar to this one in the link so you can adjust. Not sure how many 2x8 you are using. Possibly two together? In any case, this post cap will adjust total width of your 2x8s. https://www.idealtruevalue.com/store/p/165640-LPC4Z-4x-Adjustable-Post-Cap-Z-Max-Adjustable-Design-Allows-Greater-Co.aspx?feed=Froogle&gclid=CjwKCAjw7e_0BRB7EiwAlH-goCAME3Wt3bzq5fMKiYEbbbCbR6Vsj_Q8q9HIteOrpU87900mWt9lsBoCPSwQAvD_BwE
The holes in the A23Z are 0.171" diameter and the only approved screw for this connector to be installed with is the #9 x 1 1/2" Strong-Drive® SD Connector screw. Thank you!