Where to add a snippet for a popup on my Shopify site

HI , I need an easy reply to my issue as i’m not very computer savvy . I tried to add a snippet for a Kaviyo pop up into theme.liquid in my shopify account where the video suggested to add it but it didnt work - just above </body >  and </html. which was on line 143 but i have a few more additions of lines for Afterpay which goes all the way to maybe line 182 . should i be scrolling all the way past the Afterpay stuff and add it in the bottom ??? Thank you