1. You barrier way too much. Try to only use it if you need to push them away, block air unblockables, or protect your last primer, cause otherwise, it just takes you closer to the Danger State, which is NO fun for Ragna.
2. You were being too passive. The Lambda match up is one where you will have to block a lot, but there where many chances you could have taken to get in, and still be safe. For instance, high or double jumping forward instead of air dashing in. Both get you closer, but air dashing is riskier, and way easier for Lambda to successfully punish. Don't throw out your normals either in hopes that it will land. Wait until you know you're within range to hit her, otherwise, your whiffing something and she's just gonna punish you for it.
3. Don't forget you have Inferno Divider if the Lambda gets too cocky. I didn't see you use it at all.
I think the Lambda just took advantage of you not knowing the match-up well. See if you can play against him more often, and try a cautiously aggressive approach. Keeping yourself safe, while still getting in.\