How do I reassure myself after making a major mistake at work?

I have been at my current writing and editing role for around 10 weeks now and so far I’ve adopted well. Of course I’ve gotten revisions for some minor things; but nothing really major.

I have been tasked with creating a PowerPoint describing a brand new automation tool that my team has created. In addition to that, as part of the PowerPoint, I am creating a complex flowchart that describes the process of the tool from beginning to end.

This PowerPoint has been through about five revisions now, which my teammate assured me happens all the time. However, this latest one was all on me. I was asked to resize and line up the images on the PowerPoint. They were not horribly off, but they were a little bit, and the director is very particular on how he likes them to look.

Instead of clarifying and asking for samples or actually sitting down with him, I resized the images to the best of my ability using grid lines as an aid. Today when we met, we didn’t even get through the full review because it turned out I had not done what the Director asked at all. In addition to that I had resized the images by dragging the sides instead of the corners, distorting all the content.

In terms of the flowchart, that was 10x worse. I knew we had a template for those. But I thought that I could resize the shapes if the text didn’t fit, or change the colors if I thought it looked better.

When I reviewed that with my direct teammate, he was very unhappy. I had completely changed the sizes to the point where they were distorted. We spent an hour and a half on a call where he ultimately ended up losing patience and resizing the flowchart himself because I just wasn’t getting it. He even asked at one point during the call “why are you copying and pasting these individual shapes? Why wouldn’t you have resized them in the original chart that you had?” And also asked questions to try and teach me like “what do you think is wrong with this one?”

I ultimately cost him a ton of time on his own tasks while he did something that I should have gotten the hang of the first of several times. I was even choked up by the end of the call because I was so frustrated. I sent him a long apology message at the end saying I’d do better in the future (even though he’s not my manager and just a teammate) because I don’t want him going to the manger and saying “this guy is clueless, we need to get rid of him”.

I am trying to tell myself that I’ve only been here for 10 weeks and to be easier on myself. I am not a designer - design was on the job description, but I am primarily a writer. I knew I might need some training on the design, but today was so bad, I am truly wondering whether I will now be on the chopping block or if I am overreacting.