C:\Program Files (x86)\StackifyPrefix\java\lib\stackify-java-apm.jar
C:\Program Files\Apache Software Foundation\Tomcat 9.0_Tomcat91\bin\catalina.bat
file and inserted set CATALINA_OPTS=%CATALINA_OPTS% -javaagent:"C:\\Program Files (x86)\\StackifyPrefix\\java\\lib\\stackify-java-apm.jar"
just after first set local line.My tomcat version is 9, JDK 1.8, Windows 2016
All the steps you followed are ok except one thing. When you attach this java agent with tomcat which is installed as windows service, it does not work. Follow the steps below:-
set JAVA_HOME=C:\Program Files\Java\jre1.8.0_251
set CATALINA_OPTS=%CATALINA_OPTS% -javaagent:"C:\\Program Files (x86)\\StackifyPrefix\\java\\lib\\stackify-java-apm.jar"