What is the proper way to add the mandatory attribution when using these vector graphics?

Vector Playing Cards 3.2
https://totalnonsense.com/open-source-vector-playing-cards/
Copyright 2011,2020 – Chris Aguilar – conjurenation@gmail.com
Licensed under: LGPL 3.0 - https://www.gnu.org/licenses/lgpl-3.0.html

Please use the standardized attribution text in a publicly visible fashion on a publicly accessible page.

Android or iOS App – Please use the standardized attribution text on your apps information page (app store), via your “about this app” option, or as text on your Apps splash page (if any).

Deck of playing cards – If your deck is sold online (or you have a kickstarter) please use the standard attribution in a publicly viewable manner on your main page. If you wish, you can also print the the attribution in small type somewhere on the playing card box (flap, bottom, etc.) or on on any included playing card (such as the extra cards sometimes used)

Poster, magazine, billboard, etc. – If you cannot use the proper attribution on a public ad project, please contact me for details on how to properly meet the terms of this license.

Please address any additional questions directly to me at : conjurenation@gmail.com

I would like to use these vectors graphics without Attribution. What are my options?

Non attribution licensing is available on a “per project” basis at a negotiated rate. Contact me to work out the details: conjurenation@gmail.com

Are the Cards Available in separate files (i.e. one file per card)?

Yes, you will find separated versions of the main color set (one .svg file per card) in addition to the normal “whole deck on one page” file.

Would you consider changing the license to something more permissive (MIT, Public Domain, etc)?
No

Is copyright an issue in using these images?
The images used (which have been modified for this project) have been around since the 1880’s are are sold by several other third party vendors with no copyright ramifications. I make no guarantees, but strongly believe the source images have been out of copyright for a very long time. Also, great effort has been made to avoid use of any trademarked items.

Please note the current set available here (currently Version 3.2) is copyrighted but can be used without cost under the terms of the open source